The transfer of fluids is required in many applications. For example, fluids may be sucked from or expelled into a region. One particular application for a fluid transfer system is in aquariums for which it may be desirable to transfer fluids, for example to clean the aquarium gravel.
The use of gravel in an aquarium is not only for decoration but for collection of the debris and organic wastes which settle toward the bottom of the tank. However, it is necessary to periodically remove the particulate debris and organic wastes produced by the fish and aquatic plants in the gravel in order to maintain a healthy environment for the fish.
In this respect, there are two main methods for removing the sediment accumulated in aquarium gravel. The first method comprises cleaning the gravel using a siphon tube or suction tube to remove the sediment in the gravel from above. There are several kinds of siphon tube used at present, for example, GB2110103 discloses a siphon device with a relatively wide inlet tube and a narrow siphon tube. In addition, U.S. 2009045143 discloses a gravel vacuum including a suction tube, a pre-filter tower connected to the suction tube, a filter tower, a pump and a return assembly to return the filtered water back to the tank. However, in each case, cleaning the gravel using a suction tube from above leads to problems such as interruption of the fish, the time required to clean the gravel thoroughly, excessive removal of the water and labour intensive.
The second main method for removing the sediment from the gravel is to remove the sediment from beneath the gravel, for example, using an under-gravel filter system, which may be self-cleaning to avoid the problems mentioned above. By way of example, U.S. Pat. No. 6,007,713 discloses a system comprising: screen structures which cover the bottom of an aquarium; a cleaning element slidably mounted under the screen structures; and a suction tube extending upward from the screen structures. Each screen structure has a porous top adapted to support a layer of gravel thereon in spaced relation to the bottom of an aquarium and to allow water and debris to fall into a debris receiving space. The cleaning elements may be moved back and forth by an elongated handle to wipe off the debris in the receiving space between the top screen structure and the bottom of the aquarium and push it towards the suction tube which removes the debris from the aquarium.
U.S. Pat. No. 4,921,614 also discloses an under-gravel filter system having a slidable cleaning element extending across the width of the tank between a screen structure and the bottom of the tank. In U.S. Pat. No. 4,921,614 the cleaning element pushes the debris collected between the screen and the bottom of the tank to a conduit which draws water and the debris out of the tank where it is disposed or otherwise filtered and returned to the tank. The cleaning element has a metallic bar therein which allows the bar to be moved across the bottom of the tank by a magnetic source such as a hand held magnet placed against the bottom of the tank.
In addition, U.S. Pat. No. 4,957,623 discloses a system comprising an aperture gravel-supporting floor plate mounted on the top of a frame and defines a space between the frame and the plate. A stationary guide tube extends upwardly from the floor plate. A movable suction head is located within the space and is connected to a movable siphon tube extending upwardly through the guide tube for movement back and forth to withdraw the contaminants.
Furthermore, U.S. Pat. No. 5,179,911 discloses an under-gravel cleaning apparatus that has a means for flushing the water and debris from the space between a screen structure and the bottom of the tank. This is accomplished by forcing water into one end of the space between the screen structure and the bottom of the tank through a feed tube and drawing the water out of the opposite end of the space through a tube system leading out of the bottom of the tank.
JP2003236317 discloses an aquarium cleaning system, which has a gravel placing means located immediately above a bottom part, the system comprises (a) a water flushing tube located on one end part of the aquarium containing a first tubular member which has first and second end parts and is nearly vertical, (b) a water draining tube disposed on the opposing end part of the aquarium containing a second tubular member which has first and second end parts and is nearly vertical, and (c) a water circulation tube disposed on the opposing end part of the aquarium containing a third tubular member which has first and second end parts and is nearly vertical.
In addition to the above-mentioned prior art documents, other gravel cleaning systems are disclosed in CA1231871, CA2094416 and JP2008284443.
However, the previously-proposed cleaning gravel cleaning systems or methods have not been particularly effective. There are two main reasons for this lack of success. Firstly, all the under gravel cleaning devices mentioned need the screen to match the size of the bottom of tank. Practically, this strictly limits the popularity of such devices as tanks vary in size and shape. Secondly, all the prior art documents disclose the removal of debris from the space between the structure and the bottom of the tank. As such, these documents mainly rely on gravity causing the debris to drop down through the hole of the structure to the space between the structure and the bottom of the tank. As a result the previously-proposed cleaning gravel cleaning systems do not clean the gravel thoroughly or efficiently.
The present disclosure therefore seeks to address these issues.